The invention relates to a thermostatically regulated sanitary mixer tap, with a cold water inlet, a hot water inlet, and a mixed-water outlet, with a fixed valve seat disk, with a valve disk that can be moved on the valve seat disk for volume control, with a temperature control and regulating unit that works with the valve disk to provide temperature control and regulation, with a control and regulating piston provided in the temperature control and regulating unit, with a temperature-dependent regulating element that works with the control and regulating piston, with an actuating lever and with a control lever connected to the actuating lever, whereby the valve seat disk has a cold water inlet opening connected to the cold water inlet and a hot water inlet opening connected to the hot water inlet, and the valve disk features passages that communicate with the cold water inlet opening of the valve seat disk and the hot water inlet opening of the valve seat disk, and the temperature control and regulating unit features cold and hot water inlet openings that communicate with the passages of the valve disk as well as a cold water annular space and a hot water annular space, and whereby the control and regulating piston can be placed in an initial temperature-determining position relative to the temperature control and regulating unit for purposes of temperature control and can be controlled by the regulating element in order to regulate temperature.
The prior art, on which the invention is based; includes first a thermostatically controlled sanitary mixer tap of the type basically described before, in which a control and regulating disk is provided in the temperature control and regulating unit (cf. DE-PS 35 25 052). In this connection, it has also already been mentioned to provide a control and regulating piston instead of a control and regulating disk (cf. claim 34 of DE-PS 35 25 052), without indicating in detail how the embodiment could appear with a control and regulating piston.
The thermostatically controlled sanitary mixer tap on which the invention is based and in which there is thus a control and regulating piston instead of a control and regulating disk exists only on paper (cf. U.S. Pat. No. 4,738,393, in particular FIGS. 6 to 10 and the corresponding description). Actually, the design implementation of this known sanitary mixer tap does not measure up to the requirements as regards both manufacture and function that can be and are levied on a high-quality series product, as represented by a sanitary mixer tap.